1. Field of the Invention
The present invention relates to an apparatus for copying video signals from a recording medium to another recording medium, and in particular, to a video signal copying apparatus for reproducing video signals recorded on a magnetic recording medium such as a magnetic disk, a magnetic tape, or a magnetic drum to record the reproduced video signals on another magnetic recording medium.
2. Description of the Prior Art
Recently there has been developed an electronic still camera system in which an imaging device such as a solid-state imaging device or an imaging tube is combined with a recording unit using, as a recording medium, a low-priced magnetic disk having a relatively large storage capacity, to shoot an object to record a still picture thereof on the disk rotating at a stable rotary speed. A reproduction or playback of pictures is conducted with a separate TV system or printer.
For a rotary magnetic recording medium for an electronic still camera, a disk with a small diameter is used, for example, of about 50 millimeters (mm) and with a track pitch of about 100 .mu.m, namely, 50 tracks may be recorded thereon with a track width of about 50-60 .mu.m and with a guard band width of about 50-40 .mu.m. In a recording or playback apparatus, the magnetic disk rotates at a constant rotary speed of, for example, 3,600 revolutions per minute (rpm) to achieve a recording or playback of video signals at a field or frame rate.
According to the systems proposed at the present state of art, a luminance signal of video signals occupies a high frequency band of more than 2.5 megahertz (MHz) including a synchronizing signal with frequency modulated (FM) in a frequency range from 6 MHz to 7.5 MHz. A chroma signal is subjected to a frequency modulation in the color-difference line-sequential scheme using a band lower than that used for the luminance signal with the center frequencies of the R-Y and B-Y signals set to 1.2 MHz and 1.3 MHz, respectively. Data such as a field number and a frame number may be recorded together therewith under the differential PSK (Phase Shift Keying) modulation.
The video signals recorded on a magnetic disk are read and demodulated by the playback apparatus to be encoded into signals in the standard color TV format, such as the NTSC, so as to be visually displayed on a video monitor.
There is required a useful apparatus for duplicating a magnetic disk on which video signals are thus recorded. For example, it is required that a dubbing operation of video signals be achieved through a simple operation while monitoring a picture to be copied and represented by the video signals, and that a picture resultant from the dubbing operation be immediately monitored by a simple operation.
One of the requirements for a dubbing system is a low deterioration of a signal to be recorded, and hence, a low deterioration of the quality of the reproduced picture. In addition, it is desirable that a special circuit such as an emphasis compensation circuit is not necessary to prevent the picture quality from being lowered. Editing capability of the contents to be recorded on a picture recording medium is also required. Particularly, for a commercial use in conducting duplication of such recording media, it is further required that a plurality of recording media be subjected to a dubbing operation from a single video signal source.